Riviera has some aluminum ones that are good.. HD steel SE tapers are pretty good too. I assume that you want tapered because of extreme lift and clearance in the head? Smith Bros, S&S and even andrews make good light non taper pushrods.

Smith Bros can make them to your design. Theirs are a bit of a choir to get in but they are rigid and that is a bonus and in your case essential. Much better parts than the SE current issues 18404-08, and not to hard to deal with without taking rockers apart and easy to adjust when used with EVO lower tubes.I respectfully disagree about the aluminum rods. Have had three sets of them bend with no interference in the motor when used with stout 180# springs.